Dental adhesive

Abstract

The present invention relates to an aqueous dental composition having a pH of less than 7 as well as to the use of a stabilizer for the preparation of an aqueous dental composition having a pH of less than 7. In particular, the present invention relates to an aqueous dental composition having a pH of less than 7 comprising (i) one or more polymerizable compounds having at least one polymerizable double bond; (ii) a polymerization initiator system containing a) an 1,2-diketone photoinitiator compound having a light absorption maximum in the range from 300 to 500 nm; and b) a coinitiator compound; (iii) a stabilizer of the following formula (I) and/or (II), wherein the Rs, which may be the same or different, independently represent a branched C 3-8 alkyl or alkenyl group, or a C 3-8 cycloalkyl or cycloalkenyl group, R′ represents a hydrogen atom, a C 1-6 alkyl or C 2-6 alkenyl group, or a C 1-6 fluoroalkyl or C 2-6 fluoroalkenyl group, X represents a group selected from a C 1-8 alkyl group or a C 3-8 cycloalkyl group, and n is 0, 1 or 2; and a solvent mixture comprising an organic solvent and at least 1 percent by weight of water based on the total weight of the aqueous dental composition.

The invention claimed is: 
     
       1. An aqueous dental composition having a pH of less than 7 comprising
 (i) a bis(meth)acrylamide compound; 
 (ii) a polymerization initiator system containing
 (a) an 1,2-diketone photoinitiator compound having a light absorption maximum in the range from 300 to 500 nm; and 
 (b) a coinitiator compound; 
 
 (iii) a stabilizer of the following formula (I) and/or (II): 
 
       
         
           
           
               
               
           
         
         
           wherein 
           the R, which may be the same or different, independently represent a branched C 3-8  alkyl or alkenyl group, or a C 3-8  cycloalkyl or cycloalkenyl group, 
           R′ represents a hydrogen atom, a C 1-6  alkyl or C 2-6  alkenyl group, or a C 1-6  fluoroalkyl or C 2-6  fluoroalkenyl group, 
           X represents a group selected from a C 1-8  alkyl group or a C 3-8  cycloalkyl group, and 
           n is 0, 1 or 2; and 
         
         (iv) a solvent mixture comprising an organic solvent and more than 10 percent by weight of water based on the total weight of the aqueous dental composition; 
       
       wherein the aqueous dental composition has storage stability for at least 3 days at 60° C. or 70° C. 
     
     
       2. The aqueous dental composition according to  claim 1 , wherein the stabilizer is a compound of the following formula (Ia), (Ib) or (IIa): 
       
         
           
           
               
               
           
         
         wherein the R 1 , R 2 , R 3 , R 4 , R 5  and R 6 , which may be the same or different, independently represent a methyl or an ethyl group. 
       
     
     
       3. The aqueous dental composition according to  claim 1 , wherein the polymerization initiator system further comprises one or more compounds selected from the following group:
 (1) an iodonium compound of the following formula (III):
   R 7 —I + —R 8 A −    (III)
 
 wherein 
 R 7  and R 8  
 which are independent from each other, represent an organic moiety, and 
 
 A −  is an anion; 
 
 (2) a sulfonium compound of the following formula (IV):
   R 9 R 10 R 11 S + A −    (IV)
 
 wherein 
 R 9 , R 10  and R 11  
 which are independent from each other, represent an organic moiety or wherein any two of R 9 , R 10  and R 11  form a cyclic structure together with the sulfur atom to which they are bound, and 
 
 A −  is an anion; 
 
 (3) a phosphonium compound of the following formula (V):
   R 12 R 13 R 14 P + A −    (V)
 
 wherein 
 R 12 , R 13  and R 14  
 which are independent from each other, represent an organic moiety, and 
 
 A −  is an anion; and 
 
 (4) a pyridinium salt. 
 
     
     
       4. The aqueous dental composition according to  claim 1 , wherein the organic solvent is isopropanol. 
     
     
       5. The aqueous dental composition according to  claim 1 , wherein the 1,2-diketone photoinitiator compound is selected from camphorquinone and 1,2-diphenylethane-1,2-dione, and the coinitiator is an amine. 
     
     
       6. The aqueous dental composition according to  claim 1 , wherein the stabilizer of formula (I) or (II) is a compound of the following formulae: 
       
         
           
           
               
               
           
         
       
     
     
       7. The aqueous dental composition according to  claim 1 , which contains the stabilizer in an amount from 0.001 to 3 percent by weight based on the total weight of the aqueous dental composition. 
     
     
       8. The aqueous dental composition according to  claim 1 , which contains the polymerization initiator system in an amount from 0.01 to 10 percent by weight based on the total weight of the aqueous dental composition. 
     
     
       9. The aqueous dental composition according to  claim 1 , further comprising one or more polymerizable compounds having an acidic group selected from a carboxylic acid group, sulfonic acid ester group, phosphonic acid ester groups and phosphoric acid ester group. 
     
     
       10. The aqueous dental composition according to  claim 1 , wherein the aqueous dental composition is a dental adhesive composition. 
     
     
       11. The aqueous dental composition according to  claim 1 , wherein the aqueous dental composition has a color stability as determined according to ISO 7491:2000(en). 
     
     
       12. A stabilizer of the following formula (I′) or (II): 
       
         
           
           
               
               
           
         
         wherein 
         the R, which may be the same or different, independently represent a branched C 3-8  alkyl or alkenyl group, or a C 3-8  cycloalkyl or cycloalkenyl group, 
         R′ represents a C 1-6  alkyl or C 2-6  alkenyl group, or a C 1-6  fluoroalkyl group or C 2-6  fluoroalkenyl, 
         X represents a group selected from a C 1-8  alkyl group or a C 3-8  cycloalkyl group, and 
         n is 0, 1 or 2, 
         for use in the preparation of an aqueous dental composition having a pH-value of less than 7. 
       
     
     
       13. The aqueous dental composition according to  claim 1 , wherein R′ represents a C 1-6  alkyl or C 2-6  alkenyl group, or a C 1-6  fluoroalkyl group or C 2-6  fluoroalkenyl. 
     
     
       14. The aqueous dental composition according to  claim 9 , wherein the one or more polymerizable compounds having an acidic group includes 10-methacryloyloxydecyl dihydrogen phosphate (MDP) and/or dipentaerythritol pentaacrylate phosphate (PENTA).